Prospectus Today

Fun with PECOTA

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Yesterday, we released the 2005 PECOTA projections, which can be downloaded here. PECOTA is Nate Silver's projection system, one which enhances accuracy by using not just regressions and past performance, but player characteristics such as height and weight, as well as advanced indicators such as contact rate and power relative to age and other factors. You can read more about PECOTA here.

I like to have some fun with these when they come out. For instance, here's what PECOTA thinks the home-run leaderboards will look like at the end of the year:

As you can see, PECOTA projects no one in MLB to reach 40 home runs this year. Where is Barry Bonds, you ask? PECOTA has a unique Bonds projection, figuring him to be the best player in baseball--posting a VORP of 88.1--while not qualifying for the batting title. This is reasonable, because 40-year-olds usually see their playing time diminish, but may be a tad pessimistic when it comes to Bonds, who would have to suffer a major injury to not qualify for rate stats' titles. Bonds is projected to lead MLB in batting average, OBP and slugging average if he can get to 502 plate appearances.

Behind Bonds on the list of the best players in baseball are Albert Pujols, Vladimir Guerrero and Alex Rodriguez. PECOTA loves Pujols like I love chocolate: he sits just behind Bonds with a projected VORP of 83.7, and no one else is within 20 points of VORP. Put a different way, PECOTA expects Bonds and Pujols to be two wins better than everyone else in baseball. That's dominance.

Of course, any projection system will probably conclude that Barry Bonds is good and that Guerrero and Rodriguez are the class of the American League. One of the best features of PECOTA is that it tags players with "Breakout" scores, expressed as a percentage. From the BP statistical glossary:

Breakout Rate is the percent chance that a hitter's EQR/PA or a pitcher's PERA will improve by at least 20% relative to the weighted average of his EQR/PA in his three previous seasons of performance. High breakout rates are indicative of upside risk.

Breakout rates measure change relative to a player's previously-established level of performance. For this reason, a high Breakout score can create a falsely optimistic picture for a player who has a very poor performance record. It is far easier for a player with a baseline of 40 EQR per season to improve upon that figure by 20% than it is for a player with a baseline of 100 EQR per season; as a result, his Breakout score is likely to be higher.

Some of the most notable breakout figures in this year's projections belong to PECOTA favorites--and teammates--Adam Dunn and Wily Mo Pena. PECOTA sees Dunn improving on last year's performance, jumping to .270/.395/.562 with 35 home runs. Pena, whose '04 projection was one of the biggest wins for the system, is pegged at .281/.351/.528, with 21 home runs in just 340 at-bats.

Other high-breakout players include Jonny Gomes (.265/.366/.491, 272 AB), Troy Glaus (.281/.391/.579, 345 AB) and Hee Seop Choi (.258/.374/.493, 329 AB). PECOTA's playing-time projections are very conservative; it's likely that if Gomes and Choi play this well, they would play more than indicated. Glaus' projection, of course, is held down by his recent injury-shortened seasons.

What about the guys on the mound? As with the hitters, PECOTA projects the usual suspects to be among the game's best pitchers, and is extremely conservative with projecting playing time. For example, Mark Prior, Kerry Wood and Jake Peavy are all projected to fall short of the 162 innings necessary to qualify for the ERA title. Among the players who are expected to reach that cutoff, PECOTA likes the following:

Breakouts and collapses work the same for pitchers as they do for hitters, but because of the sample sizes for relievers and other factors, they tend to dominate the list. Eric Gagne has one of the highest breakout rates in the game, and he heads a list of comparable power bullpen arms. Among starters, PECOTA sees the Cubs' Prior and Carlos Zambrano as having big breakout chances.